DES MOINES, Iowa — Iowa Attorney General Tom Miller on Monday filed another lawsuit against DeCoster Farms of Iowa, this one saying the hog lot operator illegally dumped animal waste into the state’s waterways.

The suit asks for penalties of $5,000 per day and a permanent injunction ordering DeCoster not to violate state environmental laws.

DeCoster also owns an egg farm in Turner, Maine, which has been cited by federal officials for numerous worker health and safety violations. The Labor Department is seeking $3.6 million in fines.

The Iowa lawsuit involves a hog lot DeCoster operates in Wright County designed to hold up to 16,000 hogs. It says waste was discharged into an old tile line and from there went into a tributary of the Iowa River.

The suit could mean even more serious trouble for DeCoster. State law allows enhanced penalties for hog lot operators with repeat violations.

Miller said the suit he filed Monday — if successful along with other actions — would bring DeCoster close to triggering those enhanced penalties. Such penalties could include a ban on new construction permits or loss of the protection from lawsuits filed by neighbors.

Peter DeCoster, construction supervisor of the firm, did not immediately return a phone call seeking comment on the lawsuit. In the past, company officials have charged there’s political motivation behind the suits. Miller rejects such claims.

“We’re not picking on DeCoster Farms,” Miller said. “We don’t pick on anyone.”

The suit filed Monday is the second court action Miller has filed against DeCoster. A lawsuit filed in January charges environmental violations against six DeCoster facilities. Both were filed in Wright County.

In addition to the two lawsuits, DeCoster has been named in administrative proceedings by the state Department of Natural Resources.

The company, owned by Austin DeCoster, operates at least 30 hog lots, mainly in Wright, Hamilton and Hardin counties. Those have the capacity to house 371,000 hogs.

The spill that led to Monday’s lawsuit was referred to Miller by the state’s Environmental Protection Commission.

“The suit alleges that hog waste discharged into an old drainage system tile line at the lagoon, and from there into a small stream that is a tributary of the Iowa River,” Miller said.

DeCoster has come under repeated fire from Miller and state environmental officials.